Keywords
brachial plexus - lung cancer - nerve infiltration - outcome - Pancoast tumor - surgical
resection
Introduction
The Pancoast syndrome (PS) has its name from an observation made by Henry Pancoast
(1875–1939), and is often mentioned synonymously with lung cancer, although it can
be associated with other neoplastic[1]
[2] and non-neoplastic conditions.[3]
[4]
[5]
[6]
[7]
[8] Because of its location, the syndrome is also called superior sulcus tumor. Literature presents large case series,[9] and also many single-case and small case series observations.
The PS in neurology is usually considered as composition of local pain, radicular
sensorimotor symptoms, and Horner syndrome. Several “atypical presentations” with
shoulder and neck pain, radiculopathy,[10] elbow pain, and other focal signs[11] have been described. Often the infiltration of the first rib, before invading the
brachial plexus, can erroneously point to a local pain syndrome.
Prognostically the detection of a large lung tumor with infiltration of the brachial
plexus is considered a dismal prognosis, and therapy is often restricted to supportive
and palliative care, usually dominated by pain treatment. Follow-up studies of patients
with PS show that distant metastasis also can often already be expected.[12] This case demonstrates that intervention in a multidisciplinary setting followed
by adequate pain therapy and rehabilitation can be successful in regard to survival
and also meaningful quality of life.
Case Report
A 45-year-old left-handed, nonsmoking woman came for neurologic evaluation, because
of pain radiating into her right elbow and recently developing numbness in her fifth
finger a few weeks prior to the consultation. As a magnetic resonance imaging (MRI)
of the cervical spine suggested a spine disk protrusion at cervical segment C8, an
orthopedic intervention had been planned.
She reported increasing progressive pain radiating into her right elbow for 9 months.
Sensory loss in her fourth and fifth fingers and the ulnar side of the lower arm had
evolved in the past weeks, resulting in clumsiness in her right hand. She was also
unable to lie in supine position as this induced unbearable pain radiating into the
right shoulder and trapezius muscle.
The neurologic investigation showed a right-sided Horner syndrome and a decreased
triceps jerk. The right hand had a mild atrophy of the small hand muscles mimicking
an ulnar nerve lesion with weakness of the interossei and lumbrical muscles. The sensory
deficit was in C8 distribution. There was no anhidrosis. The palpation of Erb point
was painful. Based on the clinical exam, a PS was suspected.
The patient was investigated with nerve conduction velocity (NCV) and electromyographic
(EMG) studies, which were not conclusive. Motor and sensory NCVs of the right median
and ulnar nerve were normal. The F-wave of the median nerve was normal, and the F-wave
latency of the ulnar nerve was prolonged and showed dispersion. The sensory NCV of
the right medial cutaneous antebrachii nerve was, however, absent (see [Fig. 2]). EMG showed fibrillation potentials in the right abductor digiti quinti muscle,
suggesting ongoing denervation, and confirmed the distribution of the lesion. The
EMG of the abductor pollicis brevis muscle was normal.
Computed tomographic (CT) scan and MRI of the lung and brachial plexus revealed a
large mass of the lung, infiltrating into the brachial plexus ([Fig. 1A]). Ultrasound showed a mass surrounding the brachial plexus ([Fig. 1B]). A CT-guided biopsy revealed an adenocarcinoma of the lung. The patient was in
a good condition and did not show any signs of metastatic spread. In interdisciplinary
meetings it was decided to start chemotherapy (platinum/Navelbine) and focal radiotherapy
(50 Gy) before surgery.
Fig. 1 (A) Magnetic resonance imaging of the brachial plexus axial T1 images showing axial
lung tumor with infiltration of the brachial plexus (dotted arrow). (B) Ultrasound image of the brachial plexus (long arrows), tumor (short arrows). (C) Invasion of the superior thoracic aperture by tumor *The nerve fascicle was surrounded
by tumor formations and infiltrated into the perineurium, but there was no intrafascicular
spread. (D) Microscopic evaluation of the resection medial cord with adjacent tumor formations
(arrow).
Surgery was performed by a right-sided Paulson incision, which is the standard approach
for posterior-type Pancoast tumors,[13] and the thoracic cavity was entered through the second intercostal space. A standard
upper lobe lobectomy was performed by ligating and dissecting the upper lobe vein,
the upper lobe arteries, and by stapling the right upper lobe bronchus. Subsequently,
laminectomies of Th1 to Th4 and dissections of the corresponding intercostal nerve
roots were performed. After this procedure, the extrathoracic part of the tumor was
completely mobilized ([Fig. 1C]). The medial cord of the brachial plexus appeared infiltrated by the tumor and could
not be spared to obtain clear resection margins. The cord was surrounded proximal
and distal by infiltration and transected by electrocautery. The in toto resected
tumor tissue block could be finally removed, the subclavian vessels were reconstructed
using ring-enforced polytetrafluoroethylene (PTFE) vascular grafts, and the thoracotomy
was closed.
The histologic examination of the surgical specimen confirmed the biopsy-based diagnosis
of an adenocarcinoma. The pathology report specified an invasive, moderately to poorly
differentiated adenocarcinoma of the lung with 30% vital tumor cells, 65% fibrosis,
and 5% necrosis after induction chemotherapy. The specimen of the brachial plexus
showed abundant fibrotic stroma between carcinoma formations and a thick nerve bundle
was identified. A nerve fascicle was partially surrounded by tumor formations and
showed infiltration into the perineurium. There was no intrafascicular spread ([Fig. 1D]).
The first follow-up 3 months postoperatively was characterized by severe neuropathic
pain that could be managed with conventional therapy used for neuropathic pain. The
intensity reduced over several months, and opiates could be terminated after 3 months.
Therapy with gabapentin was maintained. Clinically a prominent winging of the right
scapula, and preserved function of the C⅚ muscles was noted. The muscles of the forearm
and hand were paralyzed and the hand was held in a pseudoradial palsy fashion. The
sensory perception of the hand was crude and did not allow the discrimination of specific
qualities.
After 6 months the pain syndrome markedly improved. The neurologic findings remained
identical. Because of focused physiotherapy, she was using her affected hand and lower
arm hand as a counter bearing to execute hand movements with her left hand.
Discussion
This case shows symptoms, signs, findings, and treatment in a patient with PS syndrome.
The course of the disease had several unusual aspects as the onset of pain radiating
into the elbow 9 months previously and a spread into the right shoulder. The sensory
symptoms in the eighth cervical segment appeared late. A concomitant Horner syndrome
had appeared several months earlier, but was not recognized as such.
Clinically PS can present with uncharacteristic signs such as joint pain,[11]
[14] which causes undue delays in the diagnosis.[15]
Also in this case, the electrophysiologic studies were misleading. The NCV studies
showed normal motor and sensor conductions of the median and ulnar nerve, the medial
cutaneous antebrachial nerve NCV was missing, and also the F-wave of the ulnar nerve
was prolonged and dispersed ([Fig. 2]). The neurogenic changes in the small hand (C8/Th1) muscles confirmed an acute ongoing
denervation. The definite diagnosis was made by CT scan and MRI. Also, the ultrasound
of the brachial plexus demonstrated the plexus surrounded by tumor mass. A CT scan–guided
biopsy finally confirmed the diagnosis of adenocarcinoma.
Fig. 2 Electrophysiology, preoperatively. (A) Motor conduction of median and ulnar nerve, sensory action potential of ulnar nerve
preserved. (B) Ulnar nerve, delayed F-wave with dispersion. (C) Normal sensory conduction velocity of median nerve, absent cutaneous antebrachii
medial nerve.
Presurgically the patient received local radio- and chemotherapy, and finally underwent
lobectomy with partial resection of the brachial plexus. Invasion and destruction
of surrounding tissue by a Pancoast tumor including the brachial plexus has often
been considered as a palliative and incurable situation. In this case, the patient
had no evidence of generalized metastases and was in a younger age group and in a
good general medical condition. A combination of thoracic, plastic, and reconstructive
surgery has been reported successful in some cases[13]
[16]
[17]
[18]
[19]
[20] however, despite combined approaches, survival remains poor.[21] The histologic examination showed a thick nerve bundle of the brachial plexus embedded
in abundant fibrotic stroma between carcinoma formations. Besides, small carcinoma
formations surround the fascicle and infiltrate into the perineurium.
Recently, Davis and Knight published their series of Pancoast tumors in which resection
of the brachial plexus could be avoided by neurolysis performed by a dedicated neurosurgeon.[16] Posterior-type Pancoast tumors, which have a contact/infiltration of the neurologic
structures, are routinely operated together with a neurosurgeon in our institution.
In the described case neurolysis was considered impossible. The tumor had broad contact
to the medial cord and an infiltration of the cord could not be excluded. Therefore,
the medial cord was sacrificed to obtain clear resection margins. This procedure was
preoperatively discussed with the patient and she consented to all resulting sequelae.
Infiltration of peripheral nerves occurs in the cerebrospinal fluid space, skin tumors,
and often in ENT (ear–nose–throat) tumors. Infiltration of the nerve plexus occurs
also in the brachial and in particular the sacral plexus and rarely in other peripheral
nerves except in some types of hematologic diseases as lymphoma[1] and leukemia. The type and pattern of peripheral nerve infiltration have been classified[22] into “true nerve metastasis” within the nerve, direct invasion, invasion along the
nerve sheath, pushing and stretching and engulfing. In this case, the spread of the
tumor was engulfing as well as metastatic along the vessels. Generally, spread of
malignant cells in peripheral nerves is most frequent in hematologic conditions, rare
in cancer, and even rare in sarcoma. In general pathology autonomic nerve invasion
is observed in several tumors as pancreatic and prostate cancer and is a bad prognostic
sign.
The follow-up was primarily associated with severe neuropathic pain, which required
a treatment combination of gabapentin, amitriptyline, and opioids, and subsided within
several months to a controlled level. The postoperative status showed a good function
of the shoulder muscles, with the exception of a marked scapular winging. The hand
function showed a severe sensory and motor loss, with only a slight perception of
touch and marked trophic changes. She is able to use her upper limb by movements of
the shoulder and upper arm muscles and as a counter bearing for objects when using
her left hand. Despite this impairment, she has continued her office job 5 months
after the operation. Three years after the surgery, the patient is without any evidence
of tumor recurrence. The neuropathic pain has considerably improved.
In addition to the uncharacteristic appearance of the PS, this case demonstrates a
smooth transition from clinical findings, imaging, histopathologic findings, and postoperative
development, and demonstrates that also in a PS with perineural invasion meaningful
positive results can be obtained.
