Anterior interosseous syndrome: Difference between revisions

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{{Infobox medical condition (new)
 
{{Infobox medical condition
| name            = Anterior interosseous syndrome
| name            = Anterior interosseous syndrome
| synonyms        = '''Kiloh-Nevin syndrome I'''
| synonyms        = Kiloh-Nevin syndrome
| image          =
| field          = [[Neurology]]
| caption        =
| symptoms        = [[Weakness]] of the [[thumb]], [[index finger]], and [[middle finger]]; difficulty with [[pinch grip]]
| pronounce      =
| complications  = [[Muscle atrophy]]
| field          =  
| onset           = Sudden or gradual
| symptoms        =  
| duration        = Variable
| complications  =
| causes          = [[Nerve compression]], [[trauma]], [[inflammation]]
| onset          =
| risks          = [[Repetitive strain]], [[injury]]
| duration        =
| diagnosis      = [[Clinical examination]], [[nerve conduction study]], [[electromyography]]
| types          =
| differential    = [[Carpal tunnel syndrome]], [[pronator teres syndrome]]
| causes          =
| treatment      = [[Physical therapy]], [[splinting]], [[surgery]]
| risks          =
| prognosis      = Good with treatment
| diagnosis      =
| frequency      = Rare
| differential    =
| prevention      =
| treatment      =
| medication      =
| prognosis      =
| frequency      =
| deaths          =
}}
'''Anterior interosseous syndrome'''  is a medical condition in which damage to the [[anterior interosseous nerve]] (AIN), a distal motor and sensory branch of the [[median nerve]], classically with severe weakness of the pincer movement of the thumb and [[index finger]], and can cause transient pain in the wrist (the terminal, sensory branch of the AIN innervates the bones of the [[carpal tunnel]]).
 
Most cases of AIN syndrome are now thought to be due to a transient [[neuritis]], although compression of the AIN in the forearm is a risk, such as pressure on the forearm from immobilization after shoulder surgery.  Trauma to the median nerve or around the proximal median nerve have also been reported as causes of AIN syndrome.
 
Although there is still controversy among [[upper extremity]] surgeons, AIN syndrome is now regarded as a neuritis (inflammation of the nerve) in most cases; this is similar to [[Parsonage–Turner syndrome]].  Although the exact [[Cause (medicine)|etiology]] is unknown, there is evidence that it is caused by an immune-mediated response that can follow other illnesses, such as [[pneumonia]] or severe [[viral illness]].
 
Studies are limited, and no [[randomized controlled trial]]s have been performed regarding the treatment of AIN syndrome.  While the natural history of AIN syndrome is not fully understood, studies following patients who have been treated without surgery show that symptoms can resolve starting as late as one year after onset.  Other [[retrospective studies]] have concluded that there is no difference in outcome in surgically versus nonsurgically treated patients.  The role of surgery in AIN syndrome remains controversial.  Indications for considering surgery include a known space-occupying lesion that is compressing the nerve (a mass) or fascial compression, and persistent symptoms beyond 1 year of conservative treatment.
 
== Symptoms ==
 
Patients may experience poorly localised, transient pain in the wrist, ie where the sensory branch of the AIN is mapped in the brain. The pain is sometimes referred into the [[cubital fossa]] and elbow pain has been reported as being a primary complaint.<ref name="ReferenceA">Rask, M R. "Anterior interosseous nerve entrapment: (Kiloh-Nevin syndrome) report of seven cases." Clinical Orthopaedics and Related Research, no. 142: 176-81. {{PMID|498633}}.
</ref><br />⁠
The characteristic severe impairment of the pincer movement of the thumb and index finger is most striking.
 
=== Clinical signs ===
 
In a pure lesion of the anterior interosseous nerve there is weakness of the long [[flexor muscle]] of the thumb ([[Flexor pollicis longus]]), the deep flexor muscles of the index  and middle fingers ([[Flexor digitorum profundus]] I & II), and the [[pronator quadratus]] muscle.<ref name="ReferenceB">Gessini, L, L Bove, B Jandolo, C Landucci, and A Pietrangeli. "[Anterior interosseus nerve syndrome (Kiloh-Nevin) (author's transl)]." Rivista Di Patologia Nervosa E Mentale 101, no. 1: 1-11. {{PMID|7244544}}.
</ref><ref name="ReferenceC">Stern, M B. "The anterior interosseous nerve syndrome (the Kiloh-Nevin syndrome). Report and follow-up study of three cases." Clinical Orthopaedics and Related Research, no. 187: 223-7. {{PMID|6744722}}.</ref>
 
There is no sensory deficit since the anterior interosseous nerve has no cutaneous branch to skin, but there is a large sensory branch to the volar carpus, and transient wrist pain may be experienced.<ref name=WOSM>{{cite web|title=Anterior Interosseous Nerve Syndrome |url=http://www.wosm.com/index.php/component/content/article/113-anterior-interosseous-nerve-syndrome |work=Health Library |publisher=Washington Orthopaedics & Sports Medicine |accessdate=16 May 2012 |url-status=dead |archiveurl=https://web.archive.org/web/20140813062913/http://www.wosm.com/index.php/component/content/article/113-anterior-interosseous-nerve-syndrome |archivedate=13 August 2014 }}</ref>
 
== Causes ==
 
Injuries of the forearm with compression of the nerve from swelling is the most common cause: examples include [[supracondylar fracture]]s, often associated with haemorrhage into the deep musculature; injury secondary to open reduction of a forearm fracture; or dislocation of the elbow.⁠⁠<ref>Penkert, G, and D Schwandt. "[A case of anterior interosseus nerve lesion (Kiloh-Nevin syndrome)]." Handchirurgie 12, no. 1-2 (1980): 19-21. {{PMID|7250795}}.</ref><ref name="Van Der Wurff 1984">Van Der Wurff, P, R H Hagmeyer, and W Rijnders. "Case Study: Isolated Anterior Interosseous Nerve Paralysis: The - Kiloh-Nevin Syndrome." The Journal of Orthopaedic and Sports Physical Therapy 6, no. 3 (1984): 178-80. {{PMID|2065}}.</ref>
 
Direct trauma from a penetrating injury such as a [[stab wound]] is a possible cause for the syndrome.{{citation needed|date=February 2020}}
 
Fibrous bands or [[Arcuate ligament~arcuate (curved) ligaments]] may entrap the median as well as the anterior interosseous nerve, in which case a patient may experience hand numbness as well as wrist pain.⁠⁠<ref name="ReferenceA" /><ref>Knight, C R, and P Kozub. "Anterior interosseous syndrome." Annals of Plastic Surgery 3, no. 1 (July 1979): 72-6. {{PMID|543635}}.</ref>
 
Very similar syndromes can be caused by more proximal lesions, such as [[brachial plexus]] [[neuritis]].⁠<ref name="Schollen, Wilfried 2007">Schollen, Wilfried, Ilse Degreef, and Luc De Smet. "Kiloh-Nevin syndrome: a compression neuropathy or brachial plexus neuritis?." Acta Orthopaedica Belgica 73, no. 3 (June 2007): 315-8. {{PMID|17715720}}.
</ref>
 
Anterior interosseous nerve entrapment or compression injury remains a difficult clinical diagnosis because it is mainly a motor nerve problem, and the syndrome is often mistaken for index finger and/or thumb tendon injury.⁠<ref name="Rosenberg, J N 1990">Rosenberg, J N. "Anterior interosseous/median nerve latency ratio." Archives of Physical Medicine and Rehabilitation 71, no. 3 (March 1990): 228-30. {{PMID|2317141}}.</ref>
 
== Anatomy ==
 
{{main|Anterior interosseous nerve}}
 
The [[anterior interosseous nerve]] is a branch of the median nerve, with a large sensory branch to the wrist bones, which arises just below the elbow. It passes distally, anteriorly along the [[Interosseous membrane of forearm|interosseous membrane]] and innervates [[Flexor pollicis longus muscle|flexor pollicis longus]], [[Flexor digitorum profundus muscle|flexor digitorum profundus]] to index and middle finger as well as [[Pronator quadratus muscle|pronator quadratus]], and supplies sensory feedback from the wrist bones, ie the carpal tunnel, not skin.
 
== Diagnosis ==
 
Electrophysiologic testing is an essential part of the evaluation of anterior interosseous nerve syndrome. [[Nerve conduction studies]] may be normal or show pronator quadratus latency.⁠⁠<ref name="Rosenberg, J N 1990"/>
[[Electromyography]] (EMG) is generally most useful and will reveal abnormalities in the flexor pollicis longus, flexor digitorum profundus I and II and pronator quadratus muscles.⁠⁠<ref name="ReferenceB" /><ref name="Rosenberg, J N 1990"/>
 
The role or [[MRI]] and [[ultrasound imaging]] in the diagnosis of Kiloh-Nevin syndrome is unclear.⁠<ref>Roggenland, D, C M Heyer, M Vorgerd, and V Nicolas. "[Nervus interosseus anterior syndrome (Kiloh-Nevin syndrome)--diagnosis with MRI]." RöFo: Fortschritte Auf Dem Gebiete Der Röntgenstrahlen Und Der Nuklearmedizin 180, no. 6 (June 2008): 561-2. {{PMID|18584776}}.
</ref><ref>Martinoli, Carlo, Stefano Bianchi, Francesca Pugliese, Lorenzo Bacigalupo, Cristina Gauglio, Maura Valle, et al. "Sonography of entrapment neuropathies in the upper limb (wrist excluded)." Journal of Clinical Ultrasound: JCU 32, no. 9: 438-50. {{doi|10.1002/jcu.20067}}.
</ref>
 
If asked to make the "OK" sign, patients will make a triangle sign instead. This 'pinch-test' exposes the weakness of the flexor pollicis longus muscle and the flexor digitorum profundus I leading to weakness of the flexion of the distal phalanges of the thumb and index finger. This results in impairment of the pincer movement and the patient will have difficulty picking up a small item, such as a coin, from a flat surface.<ref name="Van Der Wurff 1984"/><ref>Spinner, M. "The functional attitude of the hand afflicted with an anterior interosseous nerve paralysis." Bulletin of the Hospital for Joint Diseases 30, no. 1 (April 1969): 21-2. {{PMID|5348010}}.</ref>
 
=== Ericson's Test===
 
Ericson's Test<ref>“Median Nerve Entrapments,” Ericson WB, Singh V, in “Peripheral Nerve Entrapments: Clinical Diagnosis and Management,” Trescot AM, Editor. Springer, April 2016, p369-382</ref><ref>“Management of Compressive Neuropathies of the Upper Extremity,” Kalliainen LK, Ericson WB, in “Grabb and Smith’s Plastic Surgery, 8th Edition”, Chung K et al editors, Lippincott Williams & Wilkins, 2018. Chapter 70.</ref> is a clinical maneuver for assessing the strength of the FDP and FPL muscles in anterior interosseous nerve syndrome, and other proximal entrapments of the median nerve.
 
In contrast to the "OK sign," Ericson's test isolates the action of the FDP and FPL while eliminating the contribution of the [[wikipedia:https://en.m.wikipedia.org/wiki/Tenodesis_grasp|tenodesis effect]] and other adaptations that patients may use, usually unconsciously, to augment distal pincer strength.  Failing to control for compensatory wrist tenodesis  can mask an underlying proximal median nerve weakness in a patient who can otherwise make a normal OK-sign.
 
While facing the patient in what resembles an [[arm wrestling]] stance, with elbows planted firmly on a level surface and maintained touching the [[thorax]], the examiner uses one hand to lock the patient's wrist in neutral, around which the patient curls his fingers. With the other hand, the examiner then attempts to "peel" back the tips of each individual finger against patient resistance. It is crucial that motion of the upper extremity be restricted to the distal IP joint, and that the MP and PIP joints are in full flexion and wrist neutral or slightly flexed. If the distal flexors of the index finger and thumb are weak, the patient will be unable to resist this motion, and Ericson's test is considered positive for proximal median nerve weakness. <ref> "Dual Oblique Skin Incisions For Proximal Median Entrapment" W.B. Ericson </ref>
 
Ericson's test is frequently positive for proximal median nerve weakness (of which AIN syndrome is but one subtype) even in the context of normal imaging, EMG, and nerve conduction studies, which highlights the clinical nature of the diagnosis. Overreliance on electrical diagnostic workup unfairly excludes patients who would otherwise benefit from surgical decompression.
 
== Treatment ==
 
Surgical decompression can give excellent results if the clinical picture and the EMG suggest a compression neuropathy.<ref name="ReferenceC"/><ref>Nigst, H, and W Dick. "Syndromes of compression of the median nerve in the proximal forearm (pronator teres syndrome; anterior interosseous nerve syndrome)." Archives of Orthopaedic and Traumatic Surgery. Archiv für Orthopädische und Unfall-Chirurgie 93, no. 4 (April 30, 1979): 307-12. {{PMID|464765}}.
</ref><ref>Souquet, R, M Mansat, and J P Chavoin. "[Median nerve compression syndrome at the elbow (author's transl)]." La Semaine Des Hôpitaux: Organe Fondé Par l'Association D'enseignement Médical Des Hôpitaux De Paris 58, no. 17 (April 29, 1982): 1060-4. {{PMID|6285484}}.
</ref>
In brachial plexus neuritis, conservative management may be more appropriate.<ref name="Schollen, Wilfried 2007" />
Spontaneous recovery has been reported, but is said to be delayed and incomplete.<ref name="Van Der Wurff 1984"/><ref>Crawford, J P, and W J Noble. "Anterior interosseous nerve paralysis: cubital tunnel (Kiloh-Nevin) syndrome." [[Journal of Manipulative and Physiological Therapeutics]] 11, no. 3 (June 1988): 218-20. {{PMID|3392477}}.
</ref>
 
There may be a role for [[physiotherapy]] in some cases, and this should be directed specifically towards the pattern of pain and symptoms. Soft tissue massage, stretches and exercises to directly mobilise the nerve tissue may be used.⁠<ref>Internullo, G, A Marcuzzi, R Busa, C Cordella, and A Caroli. "Kiloh-Nevin syndrome: a clinical case of compression of the anterior interosseous nerve." La Chirurgia Degli Organi Di Movimento 80, no. 3: 345-8. {{PMID|8681687}}.
</ref>
== History ==
 
The syndrome was first described by Parsonage and Turner in 1948⁠<ref>PARSONAGE, M J, and J W A TURNER. "Neuralgic amyotrophy; the shoulder-girdle syndrome." Lancet 1, no. 26 (June 26, 1948): 973-8. {{PMID|18866299}}.</ref> and further defined as isolated lesion of the anterior interosseous nerve by Leslie Gordon Kiloh and Samuel Nevin in 1952.<ref>KILOH, L G, and S NEVIN. "Isolated neuritis of the anterior interosseous nerve." British Medical Journal 1, no. 4763 (April 19, 1952): 850-1. {{PMC|2023229}}.</ref>
 
== References ==
{{Reflist}}
== External links ==
{{Medical resources
| DiseasesDB    = 
|  ICD10          = G56.0, G56.1
|  ICD9          = {{ICD9|354.0}}, {{ICD9|354.1}}
|  ICDO          = 
|  OMIM          = 
|  MedlinePlus    = 
|  eMedicineSubj  = 
|  eMedicineTopic = 
|  MeshID        =  
}}
}}
{{PNS diseases of the nervous system}}
{{Short description|A neuropathy affecting the anterior interosseous nerve}}
 
'''Anterior interosseous syndrome''' (AIS) is a medical condition characterized by the impairment of the anterior interosseous nerve, a branch of the [[median nerve]]. This condition results in weakness of the muscles innervated by this nerve, leading to specific functional deficits in the hand and forearm.
==Anatomy==
The [[anterior interosseous nerve]] is a motor branch of the median nerve that originates in the forearm. It supplies the [[flexor pollicis longus]], the lateral half of the [[flexor digitorum profundus]], and the [[pronator quadratus]]. These muscles are responsible for flexion of the thumb and index finger, as well as pronation of the forearm.
==Causes==
Anterior interosseous syndrome can be caused by various factors, including:
* [[Trauma]]: Direct injury to the forearm can damage the anterior interosseous nerve.
* [[Compression]]: The nerve may be compressed by anatomical structures such as the [[pronator teres]] muscle or fibrous bands.
* [[Inflammation]]: Conditions such as [[neuritis]] can lead to inflammation and subsequent dysfunction of the nerve.
* [[Iatrogenic]]: Surgical procedures in the forearm region may inadvertently affect the nerve.
==Symptoms==
The primary symptoms of anterior interosseous syndrome include:
* Weakness in the [[flexor pollicis longus]] and the lateral half of the [[flexor digitorum profundus]], leading to difficulty in flexing the thumb and index finger.
* Inability to perform the "[[pinch grip]]" between the thumb and index finger.
* Weakness in the [[pronator quadratus]], affecting forearm pronation.
* Absence of sensory loss, as the anterior interosseous nerve is purely motor.
==Diagnosis==
Diagnosis of anterior interosseous syndrome is primarily clinical, based on the characteristic motor deficits. [[Electromyography]] (EMG) and [[nerve conduction studies]] can be used to confirm the diagnosis and assess the extent of nerve involvement. Imaging studies such as [[MRI]] may be employed to identify any compressive lesions.
==Treatment==
Treatment options for anterior interosseous syndrome include:
* [[Conservative management]]: Rest, splinting, and physical therapy may be effective in mild cases.
* [[Medications]]: Nonsteroidal anti-inflammatory drugs (NSAIDs) can help reduce inflammation and pain.
* [[Surgical intervention]]: In cases where conservative treatment fails, surgical decompression of the nerve may be necessary.
==Prognosis==
The prognosis for anterior interosseous syndrome varies depending on the underlying cause and the timeliness of treatment. Early intervention often leads to better outcomes, with many patients experiencing significant improvement in function.
==Related pages==
* [[Median nerve]]
* [[Peripheral neuropathy]]
* [[Nerve compression syndrome]]
[[Category:Neurological disorders]]
[[Category:Neurological disorders]]
[[Category:Mononeuropathies of upper limb]]
[[Category:Peripheral nervous system disorders]]
[[Category:Syndromes]]
{{dictionary-stub1}}
{{No image}}
__NOINDEX__

Latest revision as of 22:21, 3 April 2025


Anterior interosseous syndrome
Synonyms Kiloh-Nevin syndrome
Pronounce N/A
Specialty N/A
Symptoms Weakness of the thumb, index finger, and middle finger; difficulty with pinch grip
Complications Muscle atrophy
Onset Sudden or gradual
Duration Variable
Types N/A
Causes Nerve compression, trauma, inflammation
Risks Repetitive strain, injury
Diagnosis Clinical examination, nerve conduction study, electromyography
Differential diagnosis Carpal tunnel syndrome, pronator teres syndrome
Prevention N/A
Treatment Physical therapy, splinting, surgery
Medication N/A
Prognosis Good with treatment
Frequency Rare
Deaths N/A


A neuropathy affecting the anterior interosseous nerve


Anterior interosseous syndrome (AIS) is a medical condition characterized by the impairment of the anterior interosseous nerve, a branch of the median nerve. This condition results in weakness of the muscles innervated by this nerve, leading to specific functional deficits in the hand and forearm.

Anatomy[edit]

The anterior interosseous nerve is a motor branch of the median nerve that originates in the forearm. It supplies the flexor pollicis longus, the lateral half of the flexor digitorum profundus, and the pronator quadratus. These muscles are responsible for flexion of the thumb and index finger, as well as pronation of the forearm.

Causes[edit]

Anterior interosseous syndrome can be caused by various factors, including:

  • Trauma: Direct injury to the forearm can damage the anterior interosseous nerve.
  • Compression: The nerve may be compressed by anatomical structures such as the pronator teres muscle or fibrous bands.
  • Inflammation: Conditions such as neuritis can lead to inflammation and subsequent dysfunction of the nerve.
  • Iatrogenic: Surgical procedures in the forearm region may inadvertently affect the nerve.

Symptoms[edit]

The primary symptoms of anterior interosseous syndrome include:

Diagnosis[edit]

Diagnosis of anterior interosseous syndrome is primarily clinical, based on the characteristic motor deficits. Electromyography (EMG) and nerve conduction studies can be used to confirm the diagnosis and assess the extent of nerve involvement. Imaging studies such as MRI may be employed to identify any compressive lesions.

Treatment[edit]

Treatment options for anterior interosseous syndrome include:

  • Conservative management: Rest, splinting, and physical therapy may be effective in mild cases.
  • Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) can help reduce inflammation and pain.
  • Surgical intervention: In cases where conservative treatment fails, surgical decompression of the nerve may be necessary.

Prognosis[edit]

The prognosis for anterior interosseous syndrome varies depending on the underlying cause and the timeliness of treatment. Early intervention often leads to better outcomes, with many patients experiencing significant improvement in function.

Related pages[edit]

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